1. Field of Invention
The invention relates to a three-dimensional image measuring apparatus. More particularly, the invention relates to an optical configuration in the three-dimensional image measuring apparatus.
2. Description of Related Art
The application of two-dimensional automatic optical inspection (AOI) in the printed circuit board assembly (PCBA) process has reached quite a mature stage. The two-dimensional inspection technology involves performing PCBA inspection using one or more image-capturing apparatuses in coordination with multi-color angle light, so as to manage and control PCBA quality. However, in recent years, due to increased inspection requirements, three-dimensional measuring technology is being gradually adopted, and is replacing the conventional two-dimensional automatic optical inspection technology as it is able to overcome the limitations or disadvantages thereof.
With respect to the method of measuring a three-dimensional shape of an object under measurement, a common conventional measuring method, for example that using fringe pattern projection, involves projecting a structure light of parallel sinusoid strips pattern onto the object under measurement by a projecting module, and based on a phase-shift method, reconstructs the three-dimensional shape of the object under measurement from the reflection image thereof.
In the phase-shift method, a plurality (3 or more) of reflection images from the structure light of parallel sinusoid strips pattern are first captured, and these reflection images can be analyzed taking into consideration a form of the structure light of parallel sinusoid strips pattern and a height of a measurement plane to reconstruct the three-dimensional shape of the object under measurement.